ADIPOQ-Adiponectin | Elisa - Clia - Antibody - Protein

Background

Adiponectin is a hormone and adipokine whch is produced and secreted by adipocytes. It plays a significant role in regulating several metabolic processes , including glucose regulation and fatty acid oxidation. Adiponectin levels are inversely correlated with obesity. Adiponectin enhances insulin sensitivity, which means it helps to respond better to insulin and regulate blood sugar levels more effectively. Low levels of adiponectin are associated with insulin resistance, a key feature of type 2 diabetes. Adiponectin has anti-inflammatory properties, helping to reduce inflammation in various tissues and organs. Chronic inflammation is implicated in the development of several diseases, including cardiovascular disease and metabolic syndrome. Adiponectin is thought to have protective effects on the cardiovascular system. It can help prevent the development of atherosclerosis (hardening of the arteries) by reducing the buildup of plaque in the blood vessels Adiponectin also plays a role in the regulation of energy metabolism by promoting the oxidation of fatty acids in muscle tissue and the liver. This helps to prevent the accumulation of fat in tissues.

Protein Structure

Adiponectin is a 30 kDa protein that circulates in the blood in various forms:

• Low-Molecular-Weight (LMW): Trimers.
• Medium-Molecular-Weight (MMW): Hexamers.
• High-Molecular-Weight (HMW): Multimers (12-18 subunits).

The structure of adiponectin consists of:

• Signal Peptide: Directs the protein to the secretory pathway.
• Collagenous Domain: Contains glycine-X-Y repeats, essential for the formation of higher-order multimers.
• Globular Domain: Responsible for binding to adiponectin receptors and mediating most of its metabolic effects.

Classification and Subtypes

Adiponectin does not have subtypes in the traditional sense but exists in different multimeric forms that have varying biological activities. The HMW form is considered the most active in terms of insulin-sensitizing and anti-inflammatory effects.

Function and Biological Significance

Adiponectin is involved in a range of metabolic processes:

1. Glucose Regulation: Enhances insulin sensitivity, promoting glucose uptake in tissues and reducing gluconeogenesis in the liver.
2. Lipid Metabolism: Increases fatty acid oxidation and decreases lipid synthesis, promoting overall lipid catabolism.
3. Anti-inflammatory Effects: Suppresses the production of pro-inflammatory cytokines and enhances the anti-inflammatory response.
4. Cardiovascular Protection: Plays a role in protecting endothelial cells and reducing the risk of atherosclerosis.

Interactions

Adiponectin exerts its effects through interactions with specific receptors and signaling pathways:

1. Receptors:

• AdipoR1: High affinity for the globular domain of adiponectin, predominantly expressed in skeletal muscle.
• AdipoR2: Intermediate affinity for both globular and full-length adiponectin, predominantly expressed in the liver.
• T-cadherin: Binds to the hexameric and HMW forms, facilitating signaling and cellular adhesion processes.

1. AMPK Pathway: Activation of AMP-activated protein kinase (AMPK) enhances glucose uptake and fatty acid oxidation.
2. PPAR-α Pathway: Activation leads to increased fatty acid combustion and energy expenditure.
3. Inflammatory Pathways: Inhibits NF-κB signaling, reducing the production of pro-inflammatory cytokines.

Clinical Significance

1. Metabolic Syndrome: Low levels of adiponectin are associated with obesity, insulin resistance, and type 2 diabetes. It is considered a biomarker for metabolic health.
2. Cardiovascular Disease: Reduced adiponectin levels are linked to an increased risk of cardiovascular diseases, including hypertension, atherosclerosis, and coronary artery disease.
3. Non-alcoholic Fatty Liver Disease (NAFLD): Adiponectin has protective effects against NAFLD by promoting lipid metabolism and reducing liver inflammation.
4. Inflammatory Conditions: Due to its anti-inflammatory properties, adiponectin is being studied for its role in conditions such as rheumatoid arthritis and inflammatory bowel disease.

Summary

Adiponectin, encoded by the ADIPOQ gene, is a crucial hormone secreted by adipose tissue that regulates glucose levels and fatty acid breakdown. It circulates in various multimeric forms, with the high-molecular-weight form being the most biologically active. Adiponectin enhances insulin sensitivity, promotes lipid metabolism, exerts anti-inflammatory effects, and provides cardiovascular protection. It interacts with specific receptors, activating pathways such as AMPK and PPAR-α, and inhibiting inflammatory signaling. Clinically, low adiponectin levels are associated with metabolic syndrome, cardiovascular diseases, NAFLD, and other inflammatory conditions, making it a significant biomarker and potential therapeutic target for metabolic health.